Updated March 13, 2023
Introduction to DB2 purescale
DB2 purescale is the environment provided in DB2, which helps distribute your application data across multiple servers. In short, this is the distributed database system that has some amazing features like application transparency with extreme capacity. It has less cost and risk associated when expanding and extending our distributed data to manage the increasing overload. One of the most promising features of DB2 purescale is continuous availability. This article will study the necessity of the DB2 purescale environment, its features, and its components.
The necessity of purescale
Most often, when you use the database-based application, and there is growing and increasing data created which needs to be managed for your application, it is required that you do some changes in your application and the way in which your data is being distributed. This kind of work is not scaled transparently. This will lead to great cost and time penalties for even small changes made in the application, which will ultimately affect the availability of your system and which directly or indirectly also affects customer retention as the quality of your product seems to be degraded on the user end.
DB2 purescale is thus necessary to make sure the system availability in distributed database applications. In purescale, the members of the database, which are database servers, work in a clustered system that processes the request which comes to the database system and shares the data internally. Therefore, whenever there is a requirement to increase the database capacity due to business needs, we can find more data members transparently in purescale. This does not involve changes to be made to the application or redistribution of the data in order to tune performance parameters.
Even under extreme circumstances with a huge workload, the DB2 purescale works completely fault-tolerantly and sustains all incoming database requests efficiently because it integrates advanced software and hardware technologies in its design. The features of purescale are built on design proven from DB2 for z/OS.
Installation of DB2 purescale
The installation of purescale is done from the single host, which also configures all the remaining hosts. The most important software components of purescale are as listed below –
- Cluster file system based on spectrum scale.
- DB2 members.
- IBM Tivoli System Automation-based DB2 cluster instance management software for multiple platforms.
- Cluster catching functionality providing component.
The installation of DB2 purescale starting from a single host, which in turn does the installation and configuration of other hosts, which are all together included in a pure scale environment. The installation automatically configures all the softwares and also creates all the instances of DB2. The following figure shows the installation of DB2 purescale –
Components of DB2 purescale
When we deploy the purescale environment, all the software components that are tightly integrated with the features of DB2 purescae automatically get installed, which helps in providing the highly available database solution. All the infrastructure which are required is provided by cluster catching facilities and the members, which also help in processing all the database requests. Furthermore, all the data is stored inside the shared disk storage. This makes sure that all the members can access the data easily. The key components of the DB2 purescale, which form the major part of the environment, are as shown in the below figure.
The components of DB2 purescale and their usage and functionality are as shown in the below table –
| Component | Functionality |
| DB2 Members | Whenever the DB2 client makes a request, it is automatically routed to the data member with the lowest workload, ensuring that the request is processed as fast as possible. The members read and write the data from the same database, which is stored in shared disks. Each member has its own db2sysc threads and process. |
| Cluster Catching facility (CF) | The DB2 purescale has a component called CF, a cluster-catching facility that helps manage and coordinate the locking system with the help of a global lock manager, which helps ensure that there is no conflict between two or more data members while accessing the same table data. The CF is also used for maintaining consistency in page caching by using a group buffer pool shared across all the data members of purescale. |
| DB2 Cluster Services | The software named cluster services is responsible for detecting any failure in the environment and responds with the protocol for heartbeat detection, which in turn alerts all the data members and CF and then feces the shared storage and restarts the component. This component also provides the file system for the cluster, enabling access to the common file system for all the DB2 purescale. While installing, IBM spectrum scale software for creating the cluster file system on shared disk. |
| Shared Disk Storage | The storage done on disks is shared by all the components and is used to set up multiple instances in DB2. In addition, the disk storage is used for storing database data, logs, metadata, archives, backups, instance configuration, problem determination info, and to decide the components that will still function even if there is a severe communication failure. |
| Network Connectivity | Three types of networks are necessary while using the DB2 purescale. The first one is the storage area network, also referred to as SAN, which is used to access the shared storage disk for access by data members and cluster caching facilities. The second type of network used is a high speed interconnect and low latency network for communication between CF and data members. Three types of protocols are required for this network: Remote Direct Memory Access (RDMA) protocol over Infiniband network, RDMA over RoCE network, and TCP/ IP protocol over an ethernet network. The third type of network used is the corporate network for communication between db2 instances and db2 clients. |
Conclusion
The DB2 purescale is the environment used for a distributed database management system that provides high availability and fault tolerance. It also has a transparent scaling feature whereby extending the database servers becomes very easy when required by business changes or changes related to the application’s working. Also, no or minimal changes are required to be done in the application when any change is made to the database system.
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